Wafers (also referred to as substrates) in high temperature chambers can have backside layers that are susceptible to outgassing or sublimation. The sublimates or volatilized film components or contaminants can attack chamber hardware in a variety of manners. Outgassing dopants or silicon sublimates can coat chamber components including the reflector plates (optical reflectors?) or the pyrometers, which causes chamber drift over time and necessitates recalibration, hardware changes, or chamber cleans that result in down time. Fluorine from the backside of wafers can attack the coating on the reflector plate (reflectors), and also necessitates recalibration and eventual hardware replacement.
Rapid Thermal Processing (RTP) and other processes and hardware can suffer if the film or even the bare silicon of the back of the wafer outgasses (in the case of films) or sublimates (in the case of silicon) during the processing of the wafer. The outgassed and sublimated material can coat optics or other chamber components causing the need for replacement and/or cleaning on a too frequent basis.
Currently, methods of dealing with this are problem-specific (e.g., different reflector plate stacks for fluorine resistance, MWBC kits providing sacrificial parts for silicon sublimation or dopant outgassing).
Therefore, there is an ongoing need in the art for apparatus and methods of preventing outgassing and sublimation from wafers during processing.